Matrix sorter system

ABSTRACT

A matrix conveying system for intended use in sorting articles and related methods of conveying and sorting articles are disclosed. In one embodiment, the matrix system comprises a plurality of first endless belt or chain conveyors extending in a first direction and a plurality of second conveyors extending in a second direction, each intersecting the plurality of first conveyors. The system may be used to sort articles delivered from one or more storage locations for distribution, or may instead be used to sort articles for delivery to one or more storage locations. In another embodiment, the system comprises three levels of intersecting conveyers

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/567,411, filed Apr. 29, 2004, and Ser. No.60/618,853, filed Oct. 14, 2004, the disclosures of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the article conveying art and, inparticular, to a system including a matrix of conveyors for conveying orsorting articles.

BACKGROUND OF THE INVENTION

Over the past several years, the demand from businesses and individualsalike for second day and even overnight deliveries of articles, such assmall to mid-sized parcels, packages and letters, has steadilyincreased. This demand is due, in part, to the prevalence of Internetand mail order shopping, which creates a similar need for an efficientand effective distribution system to deliver expediently the wares to acommon carrier. Consequently, the need for methods and systems forquickly transporting, sorting and distributing this ever increasingvolume of articles has similarly increased.

In fact, it is now general practice for common carriers to transportarticles in the form of small to mid-sized packages or the like to acentral sorting terminal or hub, where they are sorted according toselected parameters, such as having common regional destinations, andthen delivered as a group. Once these destinations are reached, it isnecessary to sort again to distribute articles in the group to theirfinal destinations. To accomplish these tasks in the amount of timerequired to insure overnight delivery, the central as well as theregional sorting terminals or hubs must receive, sort and distributehundreds of thousands of coded packages each day. Besides on thedelivery side, a similar need exists on the distribution side, sincepurchasers have become accustomed to receiving ordered items withoutsignificant delay.

Necessarily, the sortation systems used must be capable of processingthe packages within these defined time parameters. Indeed, in responseto the continuously increasing number of packages requiring next day orovernight delivery, the sortation systems must operate much faster andmore efficiently than just a few years ago. It is also desirable for thesystems to be more adaptable to accommodate fluctuations in need/demand,as well as simpler and less expensive.

Since as early as the 1960's, various package sortation systems haverelied upon primitive “induction” type systems including an endless“loop” conveyor with mobile units that receive, transport and depositpackages at selected distribution stations. Specifically, U.S. Pat. Nos.3,167,192 to Harrison et al. and 3,327,836 to Burt each disclose packagesortation systems using tilt tray assembly units propelled by an endlessconveyor chain. Timers and somewhat unreliable magnetic readers actuatetip solenoids to tilt the trays to one side, thus in theory allowinggravity to pull passively the packages from atop the trays upon reachingtheir destination. As should be appreciated, the speed with which such asystem can process articles leaves much to be desired, especially sincearticles must potentially traverse the entire loop before reaching thedesired destination.

A more recent sortation system described in U.S. Pat. No. 4,832,204 toHandy et al. integrates these prior art tilt tray sortation systems withmore complicated scanning equipment and computer control in an attemptto improve overall system speed and efficiency. Despite the successfulintegration of these components into a supposedly more modern and stateof the art system, and at a cost of much greater complexity and cost,the system of the '204 patent still fails to improve the basic sortationapparatus and methods. In essence, package delivery customers arecalling for a move away from the continued reliance on the complex andexpensive tilt tray systems that rely primarily on gravity transfer,such as in the '204 patent, and at the same time demanding significantincreases in the overall speed, efficiency and adaptability of thesortation system.

In recent times, “tilt tray” sorters have been replaced by allegedlymore efficient “cross belt” sorters. One version of this type ofsortation system includes an endless train of driven cars passoperator-controlled feed conveyors used to deliver a single article fortransport around the loop. When the car reaches the desired destinationfor the article, an onboard conveyor actuates to eject the article to atakeaway conveyor. An early example of this type of system appears inU.S. Pat. No. 3,977,513 to Rushforth, and a more modern example appearsin the September 2003 issue of Modern Material Handling magazine (whichis incorporated herein by reference).

Despite the industry-wide movement toward this type of sorting system,it still suffers from similar problems with efficiency. Just like in thetilt tray systems, only a single article can be loaded onto a selectedcar at a given instant in time. This serves as a significant limitationon the total throughput possible, and requires operating many suchsystems simultaneously to keep up with the demand. The use of individualcars with cross belts, which are typically complicated in construction,also presents problems from a reliability and maintenance standpoint.

Furthermore, past sortation systems cannot sort articles continuously,since various events demand downtime. For example, articles sometimesmis-introduced into the system must be retrieved and removed. Likewise,completing the previous sorting operation before introducing the nextgroup of articles requires introducing any articles accidentally leftout from the previous operation, which results in costly downtime.Running two induction-type sortation systems in parallel alleviates theproblem in part, but this will not necessarily reduce the cost. Theexisting systems also tend to occupy a great deal of floor space, whichmay make this impossible to accomplish using a given facility.

Thus, an important aspect of the effort to improve this technologyinvolves providing a sortation system and related method capable oftransporting, sorting and distributing the increasing volume of sucharticles in a more efficient manner. The desired approach shouldeliminate the complexity, especially by eliminating tilt trays forejecting articles being conveyed at a particular location, such as alongan endless induction loop, and instead go to a simple arrangement ofendless belt or chain conveyors. Increased efficiency and adaptabilityof use, as well as lower cost and maintenance, should advantageouslyresult without a concomitant increase in complexity.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a conveyor system forintended use in conjunction with the sorting of articles comprises aplurality of first substantially continuous endless belt or chainconveyors extending in a first direction, each providing a firstconveying surface for the articles. A plurality of second substantiallycontinuous endless belt or chain conveyors extending in a seconddirection intersect the first conveyors. Each second conveyor provides asecond conveying surface for any articles transferred from one or moreof the intersecting first conveyors.

To automate the sortation process, the system preferably furtherincludes means for transferring at least one article from at least oneof the first conveyors to an intersecting one of the second conveyors.The transferring means may be provided adjacent each intersection fortransferring one or more articles from each first conveyor to theassociated second conveyor. In one embodiment, the first conveyors arepositioned above the second conveyors, and the means for transferringarticles comprises a portion of each first conveyor capable of assuminga drop down position for delivering one or more of the articles to thesecond conveyor. Preferably, an end of the drop down portion of eachfirst conveyor is staggered relative to a lateral dimension of theassociated second conveyor, which helps to avoid article collisions.

The first conveyors are parallel to each other and generallyperpendicular to the second conveyors, and may include interconnectedmodular links. Furthermore, a plurality of third conveyors may beprovided for receiving articles from the first or second conveyors,wherein the third conveyors intersect the first conveyors and extendgenerally parallel to the second conveyors. Optionally, the thirdconveyors may move the corresponding articles in a direction generallyopposite that of the second conveyors.

In accordance with a second aspect of the invention, a conveyor systemfor intended use in conjunction with the sorting of articles comprises aplurality of first conveyors extending in a first direction in a firsthorizontal plane. A second conveyor extends in a second directiongenerally perpendicular to the first direction and in a secondhorizontal plane, and further intersects the plurality of firstconveyors. Means adjacent each intersection is provided for transferringat least one article between the first and second conveyors to therebyeffect sortation.

In one embodiment, the transferring means is an L-shaped transferconveyor including a first portion aligned with the first conveyor and asecond portion aligned with the second conveyor. Preferably, the secondportion is tilted relative to a horizontal plane such that articles mayslide onto the second conveyor. Alternatively, the transferring meansmay be selected from the group consisting of an active conveyor, apassive chute, and an elevator.

The second conveyor may be positioned either below or above theplurality of first conveyors. In either case, the system may furtherinclude means for moving the at least one article from the firstconveyor to the transferring means. In one embodiment, the moving meansis a diverter associated with the first conveyor.

In accordance with another aspect of the invention, a conveyor systemfor intended use in conjunction with the sorting of articles comprises aplurality of first conveyors extending in a first direction and aplurality of second conveyors extending in a second direction. Thesecond conveyors are positioned above and intersect the first conveyors.At least one third conveyor extends in either the first or seconddirection and is positioned below the first conveyors.

Preferably, the first and second directions are generally perpendicularto each other, and the system includes means for transferring articlesfrom one first conveyor to one second conveyor. The system may furtherinclude means for transferring articles from one first conveyor to thethird conveyor. However, it is preferable to provide means fortransferring articles at each intersection between the first, second,and third conveyors.

In accordance with still another aspect of the invention, a conveyorsystem for intended use in conjunction with the sorting of articles isdisclosed. The system comprises a plurality of first conveyors extendingin a first direction; a plurality of second conveyors intersecting thefirst conveyors; and a third conveyor for transferring articles from afirst conveyor to a second conveyor at each intersection. Preferably,the third conveyor is L-shaped and includes a first portion aligned withthe first conveyor and a second portion aligned with the secondconveyor. The second portion may be tilted relative to a horizontalplane such that articles may slide onto the second conveyor.

In accordance with yet another aspect of the invention, a conveyorsystem for intended use in conjunction with the sorting of articlescomprises a plurality of first conveyors extending in a first direction,a plurality of second conveyors intersecting the first conveyors, and atleast one receiver associated with each second conveyor for receivingarticles having a particular characteristic in common. The commoncharacteristic may be, for example, a delivery destination selected fromthe group consisting of a country, region, state, zip code, county,city, village, town, and street address.

Preferably, each second conveyor is associated with a takeaway conveyorfor delivering a selected article to the receiver. The system mayfurther include a plurality of receivers, each associated with atakeaway conveyor for delivering a selected article from thecorresponding second conveyor. The takeaway conveyor may be an indexingconveyor including two or more segments, each capable of independentlyconveying an article to the corresponding receiver.

In accordance with a further aspect of the invention, a matrix sortationsystem comprises three different levels of conveyors, including a firstlevel of first conveyors, a second level of second conveyorsintersecting the first conveyors, and a third level of third conveyors.The first conveyors may be infeed conveyors and the second and thirdconveyors are takeaway conveyors. Alternatively, the first and thirdconveyors may be infeed conveyors and the second conveyors may betakeaway conveyors

In accordance with yet a further aspect of the invention, a method ofconveying articles is disclosed. The method comprises transportingarticles along a plurality of first endless belt or chain conveyorsextending in a first direction. The method further comprisestransferring an article from at least one first conveyor to one of aplurality of second conveyors extending in a second direction andintersecting the plurality of first conveyors. The method may furtherinclude the step of selecting an article for transfer to one of thesecond conveyors prior to the transferring step, which in turn maycomprise identifying a common characteristic of the article. Stillfurther, the method may include the steps of: (1) transferring thearticle from the second conveyor to a receiver; or (2) simultaneouslytransferring articles from a first conveyor to two different secondconveyors.

In accordance with yet another aspect of the invention, a method ofconveying articles comprises transporting articles along a plurality offirst conveyors extending in a first direction; transferring a firstselected article from one first conveyor to a second conveyor extendingin a second direction and positioned below the first conveyors; andtransferring a second selected article from one first conveyor to athird conveyor extending in the second direction and positioned abovethe first conveyors. The transferring steps may comprise actively orpassively conveying the corresponding article.

Still another aspect of the invention is a method of sorting articles.The method comprises providing a matrix including a first level of firstconveyors extending in a first direction, a second level of secondconveyors below the first conveyors and extending in a second direction,and a third level of third conveyors above the first conveyors parallelto the second conveyors. The method further comprises sorting a batch ofarticles delivered to the first conveyors by selectively delivering thearticles from the corresponding first conveyor to a selected one of thesecond or third conveyors. The batch of articles may include firstarticles and second articles, in which case the sorting step isperformed by delivering the first article from the corresponding firstconveyor to the selected one of the second conveyors, and thendelivering the second article from the corresponding first conveyor tothe selected one of the third conveyors.

A further aspect of the invention is a method of sorting articles. Themethod comprises providing a matrix comprised of a first level of firstconveyors extending in a first direction, a second level of secondconveyors below the first conveyors and extending in a second direction,and a third level of third conveyors above the first conveyors parallelto the second conveyors. The method further comprises: (1) sorting afirst batch of first articles delivered to the first conveyors byselectively delivering the first articles from the corresponding firstconveyor to a selected one of the second conveyors; and (2) sorting asecond batch of second articles delivered to the first conveyors byselectively delivering the second articles from the corresponding firstconveyor to a selected one of the third conveyors. The sorting of thefirst and second batches may be done simultaneously, or instead, thesorting of the first batch of articles may be completed prior to thesorting of the second batch of articles.

In accordance with one other aspect of the invention, a method ofdelivering articles requiring sortation to a warehouse is disclosed. Themethod comprises delivering the articles to a plurality of infeedconveyors; transferring articles to one of a plurality of takeawayconveyors intersecting the infeed conveyors and associated with aparticular storage location; and delivering the articles to the storagelocation. The method may further comprise the steps of: (1) deliveringthe articles from a storage location to one of the plurality of infeedconveyors; and (2) transferring articles having a common characteristicfrom the infeed conveyor to one of the plurality of takeaway conveyors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway plan view of the sortation system formingone aspect of the invention;

FIG. 2 is a partially cutaway side view of the system of FIG. 1;

FIG. 3 is a partially cutaway side view of a takeaway conveyorassociated with the system of FIG. 1;

FIG. 4 is a perspective view showing another embodiment of the sortationsystem;

FIG. 5 is a partially cutaway top plan view of one embodiment of asub-sorting station;

FIG. 6 is a partially cutaway perspective view of a sub-sorting station;

FIG. 7 is a partially cutaway plan view of yet another embodiment of thesortation system, including three levels of conveyors;

FIG. 8 is an end view of two of the conveyors forming part of the systemof FIG. 7;

FIG. 9 is a partially cutaway side schematic view of one possible meansfor transferring articles between two conveyors; and

FIG. 10 is a partially cutaway top plan view of a transferring meanssimilar to the one shown in FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, one possible embodiment of a sorter system 10forming one aspect of the invention is schematically illustrated. Asillustrated, the sorter system 10 may comprise a “matrix” formed of aplurality of intersecting belt or chain conveyors 12, 14 extending indifferent directions. Each conveyor 12, 14 is of the endless belt orchain type, and thus provides a substantially continuous conveyingsurface for articles (as contrasted from tilt tray sorters, which unlikebelt or chain conveyors create a substantially interrupted conveyingsurface). Although certainly not a requirement, a preference exists forthe types of endless belt or chain conveyors manufactured and sold bySpan Tech, LLC under THE DESIGNER SYSTEM® trademark, the details ofwhich are found in U.S. Pat. Nos. 4,953,693 and 5,031,757 (which areincorporated herein by reference).

As a result of this arrangement, each intersection represents a possibleor potential location or point T for transferring an article between theassociated conveyors 12, 14. Consequently, two or more selected articlesconveyed along different infeed conveyors 12 extending in one directionmay undergo simultaneous sortation and delivery to one or more of thetakeaway conveyors 14 extending in a different direction and associatedwith a particular destination (such as a delivery truck, receiver, orsortation subsystem). By creating a system 10 including numerous infeedand takeaway conveyors 12, 14 extending in both directions andselectively moving articles between them at the desired intersections,article sortation can thus be achieved in a highly efficient andeffective manner, and one heretofore unknown using prior types ofendless loop induction systems.

In the embodiment shown in FIG. 1, the infeed and takeaway conveyors 12,14 of the system 10 extend generally perpendicular to each other (notefirst and second orthogonal directions D₁ and D₂) in a spaced apartfashion and thus form a “regular” grid (e.g., 4×4, although an irregulargrid (2×3, 4×5, 40×50, etc.) could easily be used as well). In thisparticular illustrated embodiment, the matrix system 10 comprises: (1) afirst set or series of infeed belt or chain conveyors 12 a-12 nextending in a first longitudinal direction (four conveyors shown,labeled 12 a-12 d); and (2) a second set or series of takeaway belt orchain conveyors 14 a-14 n extending in a second longitudinal directiontransverse to the first direction (four shown, labeled 14 a-14 d). Theseinfeed and takeaway conveyors 12, 14 preferably each associate with adistinct starting point S and ending point E (i.e., they are linear orstraight and independent from each other, as contrasted with known priorart induction systems using an endless loop conveyor with a continuoustrain of cars to effect sortation). Preferably, the conveyors 12, 14 ineach series extend generally parallel to each other, including in theportion comprising the system 10, and move in the same direction (notearrows A and B in FIG. 1) along an endless path.

As perhaps best shown in FIG. 2, the infeed conveyors 12 a-12 dgenerally lie in a first horizontal plane above the secondary ortakeaway conveyors 14 a-14 d, which are in a second, differenthorizontal plane. This provides the system 10 with multiple layers,levels, or tiers of conveyors 12, 14. In one proposed embodiment, theinfeed conveyors 12 a-12 d all lie above the takeaway conveyors 14 a-14d. However, as indicated in the description that follows, thisarrangement may be reversed or, alternatively, more than two layers ofintersecting conveyors may be used, with some above and some below eachother (see FIG. 7). Although not shown, it should be appreciated thatthe conveyors 12, 14 are all preferably supported above the ground, suchas in the manner disclosed in the '693 or '757 patents.

In accordance with another aspect of the invention, means fortransferring at least one selected article between the conveyors may beprovided at or near each intersection between a infeed conveyor 12 and atakeaway conveyor 14. In the embodiment of FIG. 1, the means fortransferring comprises a transfer conveyor 16. Preferably, the transferconveyor 16 is a generally L-shaped, driven, endless belt or chainconveyor, oriented such that the articles transferred onto it move fromthe plane of the corresponding infeed or first conveyor, such asconveyor 12 a, to the corresponding takeaway or second conveyor, such asconveyor 14 a. The use of an L-shaped transfer conveyor 16 asillustrated is especially preferred in situations where the articleshave a direction of elongation, since the article upon reaching thetakeaway conveyor 14 will normally assume the exact same orientation ithad on the infeed conveyor 12 (which may have been selected by theperson placing the articles to ensure that an indicia such as a bar codewas in a proper position for being read). However, the use of a linearor passive transfer conveyor 16, such as for example, a straight endlessconveyor or a passive slide/chute, is also possible.

To move one or more of the articles selected for transfer onto theconveyor 16, a diverter 18 may be used. The diverter 18 functions todivert or move a selected article onto the transfer conveyor 16, and maythus comprise any structure for performing this function. For example,the diverter 18 may comprise a retractable arm, gate, lug, or guide formoving into the path of a selected article on the associated infeedconveyor 12 and directing it onto the transfer conveyor 16.Alternatively, the diverter 18 may comprise a picker, kicker, pusher, orlike motive device.

As should be appreciated from the foregoing, the particular means usedto move any selected article between the conveyors 12, 14 could varydepending on the arrangement used and any special needs (e.g., conveyingdelicate articles versus books). Likewise, instead of an active transferconveyor 16, the transferring means for example may comprise a pusher,kicker, ejector, lifter, elevator, actuator or combinations thereof fortransferring an article from one conveyor to another, including inpossible combination with a chute or conveyor. Although not preferred,the possibility of using a manual “pick and place” operation at eachintersection exists (which especially helps when one or more of thetakeaway conveyors are above the infeed conveyors). In any case,selected articles reliably make their way from the infeed conveyors 12to at least one of the takeaway or secondary conveyors 14, therebyeffecting the desired sortation.

Turning back to FIG. 2, the portion or leg of the L-shaped transferconveyor 16 adjacent to and generally aligned with the takeaway conveyor14 a may be tilted relative to a horizontal plane. Advantageously, thistilting may cause an article being conveyed along the transfer conveyor16 to slide automatically onto the associated takeaway conveyor 14without the need for active engagement. A passive diverter (not shown),such as a fixed gate, may also be provided at or near the end of thisleg of the transfer conveyor 16 to help insure that any articles that donot slide off are ultimately diverted. However, instead of a tiltedarrangement with a passive diverter, it is also possible to provide anactive diverter (not shown) for moving articles from a non-tiltedsection of the conveyor 16. In order to insure that proper selection fortransfer is achieved (and thus sorting provided), articles approachingon the infeed conveyor 12 may be identified visually by an operator orusing well-known types of “machine vision” scanning technology (e.g.,reading a bar or other code using an adjacent (preferably overhead)reader 20)). Preferably, the article spacing on each infeed conveyor 12is such that only one selected article is transferred at a time.However, unlike in prior systems utilizing tilt trays running in endlessloops in which only a single article may be processed at a given instantin time, articles for delivery to common destinations may simultaneouslytransfer from different infeed conveyors 12 a-12 d to one or more of thetakeaway conveyors 14 a-14 d. More efficient sorting operation and apotential multi-fold increase in throughput without a concomitantincrease in conveying speed results.

In the case where all articles divert or transfer onto takeawayconveyors 14 a-14 n, then the infeed conveyors 12 a-12 n may simplyterminate. However, an alternative approach extends one or more of theinfeed conveyors 12 a-12 n such that articles not transferred ultimatelyreach a downstream location for further processing. For example, anarticle remaining on one infeed conveyor 12 a, such as the result ofinadvertent placement, and not actually needed to fill an order made(and thus not transferred to any of the takeaway conveyors 14 a-14 n),may reach a “reject” bin (not shown). Alternatively, such articles maycollect on a single return conveyor (not shown) extending back to anassociated storage area.

Another alternative involves delivering the articles remaining on theinfeed conveyors 12 a-12 n to another sorter system, including possiblyanother matrix system (not shown). In the latter case, a “single row”matrix may include a single endless belt or chain infeed conveyor havinga continuous conveying surface and a plurality of takeaway conveyorsintersecting this infeed conveyor. This arrangement may work well insituations where the articles are all intended for delivery to differentaddresses in the same city or zip code or otherwise share a commoncharacteristic.

Turning to FIG. 3, each takeaway conveyor 14 a . . . 14 n in the system10 may also orient at an angle, or “tilt,” relative to the horizontalplane in a direction transverse to the conveying direction, either atthe transfer point or at a downstream location. Such tilting causestransferred articles to slide down along the corresponding conveyingsurface to a known edge, which may be defined by a side guard (notshown) adjacent to the associated takeaway conveyor 14. As should beappreciated, this tilting generally turns the articles to achieve aparticular orientation (e.g., short end leading, in the case of anelongate article) for a desired operation (e.g., reading a bar code,such as using an adjacent reader 20). Once the operation is complete, itmay also be desirable as shown in FIG. 3 to provide a portion of theconveyor 14 with a “twist” section 22 that returns the article to aposition parallel with a horizontal plane before undergoing furtherprocessing.

Exemplary uses of the matrix sorter system 10 described above aremyriad. One such use involves a facility for delivering articles such asbooks from a storage location in a warehouse to a particular destination(such as to a packaging area or loading dock for shipping to retailstores). In particular, each infeed conveyor 12 associates with agrouping of books within the warehouse. A “pick to light” systemvisually identifies to a “picker” the books at the storage location inthe warehouse (such as an adjacent shelf or pallet) to place on theinfeed conveyor 12. Pickers may thus place individual books on differentinfeed conveyors 12 running in parallel or alternatively on a singleconveyor that ultimately divides into several infeed conveyorsassociated with the system 10.

In either case, the books on each infeed conveyor 12 a . . . 12 n uponapproaching the system 10 undergo identification, either by an operatoror a machine scan (in which case, a person positioned upstream of thescanning location may ensure the books are in the proper orientation andsingulated (e.g., separated by a certain minimum distance in theconveying direction)). Each takeaway conveyor 14 may be associated witha common parameter or characteristic shared by some books (e.g., thosegoing to a particular destination, company/individual, distributioncenter, store, sorting location, etc.). Once identified, thecorresponding books on the various infeed conveyors 12 are identifiedand then transferred to the correct takeaway conveyor 14 to effectsortation in the desired fashion using the above-described transfertechniques (which, again, are preferably automated, but may instead bemanual or semi-automated).

Downstream along the takeaway conveyor 14, the books may undergo furthersorting, if necessary (such as if those having different destinationsare transferred). Of course, placing persons along this conveyor 14 toidentify and move the books to packages, bins, bags, carriers, etc.works for this purpose. Alternatively, and as discussed further below,this “sub” sorting may instead use an automated system, such as one thatdetects and routes each book to an appropriate takeaway conveyor fordelivery to a receiver (e.g., bag, box or bin) representing an order.

An example of a particular sub-sorting arrangement useful with a matrixsorter system 10 essentially as described above is shown in FIGS. 4-6.FIG. 4 shows that the overall system 10 comprises a plurality (twenty)infeed conveyors 12 extending in a first direction and a plurality (ten)of takeaway conveyors 14 extending in a second direction. The takeawayconveyors 14 generally lie in a common horizontal plane, but arepositioned below the infeed conveyors 12. Each of the ten takeawayconveyors 14 associates with one or more sortation “stations” 24. In theillustrated embodiment, three such stations 24 a, 24 b, 24 c lie spacedfrom each other in the conveying direction and on the same side of acommon takeaway conveyor 14 (which it should be appreciated may be adistinct conveyor from the one forming part of the basic system 10).

Turning to FIGS. 5 and 6, it can be seen that each station 24 comprisesat least one and preferably a plurality of transverse conveyors 26 fordelivering the articles from the associated takeaway conveyor 14 to atemporary storage location corresponding to articles sharing a commoncharacteristic (e.g., those comprising a particular order, or thosegoing to a particular country, region, state, zip code, city, town,village, address, etc.). In the embodiment shown, six such substantiallycontinuous conveyors 26 a-26 f extend in parallel. Preferably, eachconveyor 26 a-26 f comprises an “indexing” conveyor including aplurality of individual conveyor segments arranged in series (with sixsegments 28 a-28 f shown for purposes of illustration only), whichtogether define each continuous conveyor. A common electric motor (notshown) may drive these segments 28 a-28 f at the same speed and in thesame direction, or alternatively separately actuated motors may drivethem independent of each other. As indicated in FIG. 5, a selectedarticle may be transferred to the leading segment 28 a of each indexingconveyor 26 a-26 f from the takeaway conveyor 14 using an associateddiverter 18.

A sensor (not shown) associated with each conveyor segment 28 a-28 f maydetect the presence of an article thereon. A conventional “photoeye”arrangement or mechanical type sensor (e.g., a weight sensor, a physicalcontact switch, etc.) may serve in this role. Upon an articletransferring from the takeaway conveyor 14 to one of the indexingconveyors 26 a-26 f, the corresponding segments 28 a-28 f run until thesensor associated with the segment 28 a closest to the storage location,or bin 30, detects the article.

In the event a second article for delivery to a second location or bin30 reaches that same indexing conveyor 26 a-26 f, that article transfersin a similar fashion. The second article conveys until it reaches thesegment 28 b upstream of the segment 28 a holding the first article,which may be held stationary. This sequence can be repeated until anarticle associates with each segment 28 a-28 f of each indexing conveyor26 a-26 f.

Once one or more of the indexing conveyors 26 a-26 f are loaded, thearticles transfer to the appropriate storage location. In theillustrated embodiment, this comprises a structure 30 including aplurality of bins 32 arranged in columns corresponding to the number ofindexing conveyors 26 a-26 f. The number of rows may be as few as one(in which case the indexing conveyor described above could be replacedwith a simple continuously running conveyor for transferring selectedarticle(s) from the takeaway conveyor 14 to the appropriate bin).However, to maximize the throughput, the number of bins preferablycorresponds at least to the number of segments on the associatedindexing conveyor, and most preferably to the number of segments 28times the number of conveyors 26. Thus, in the example where sixindexing conveyors comprise six segments each, the structure 30 is sixbins by six bins.

The outfeed end of each indexing conveyor 26 a-26 f nominally liesadjacent only one row of bins 32. If any article on the farthestdownstream indexing conveyor 26 a-26 f belongs in one of those bins(which may be known using either on the spot detection (manual orautomatic) or controls), then the corresponding indexing conveyoractuates such that the article transfers to the desired bin. Thenext-in-line article then advances as described above until the sensorassociated with the furthest downstream segment (segment 28 a in theexample) detects the article. If that article belongs in the same bin asthe preceding one (such as if both are going to a common destination orotherwise share a common characteristic), then it too transfers.

Once all articles slated for a bin in the nominal row transfer, thestructure 30 may be moved to associate the bins of another row with theoutfeed end of the indexing conveyors 26 a-26 f, and the sequencedescribed above repeats. In the case where the bins 32 are spaced bothhorizontally and vertically from each other, this may be accomplished byusing a lifter to raise and lower the structure 30 such that an articleto be transferred from the furthest downstream segment 28 a of eachindexing conveyor 26 a-26 f is positioned adjacent the correct bin, atwhich time that segment activates to effect delivery. Alternatively, thetransverse conveyors 26 may move to associate with the correct bins 32.

As illustrated, the structure 30 may be mobile, such as through theprovision of wheels 35. Once sortation ends for a given run or shift,the structure 30 may move to a location where the articles are furtherprocessed (such as for packaging). In the interim, a replacementstructure may be associated with the station 24 such that the sortationefficiency remains unhindered because of the time required to check andunload the bins.

As noted above, each structure 30 in the arrangement shown in FIGS. 4-6thus includes thirty-six bins. In this exemplary arrangement, threestructures 30 associate with each takeaway conveyor 14, and ten takeawayconveyors exist. The total number of possible sort destinations equals1,080. If the twelve rows of bins exist instead of six, this figuredoubles and thus becomes 2,160. If six stations associate with eachsecondary conveyor, it doubles again to 4,320. Then doubling the numberof takeaway conveyors (including by possibly adding a third level ofconveyors; see below) to twenty results in 8,640 possible sortaddresses, a figure unheard of using a conventional single inductionloop of any reasonable size.

An alternative to a vertical arrangement is one where the structure 30shown in FIG. 6 lies with its back 30 a parallel to the ground such thatthe bin entrances 32 a are positioned below the indexing conveyors 26a-26 f. A linear motion device could then move the structure 30 to andfro as necessary to ensure that the articles transferred from thesegments fall into the appropriate bin. Likewise, providing fewer rowsthan the number of indexing conveyors makes it necessary to move thestructure 30 in two different directions to match the next-in-linearticle with the corresponding bin.

Instead of using the arrangement shown in FIGS. 5 and 6, yet anotheroption involves accomplishing further sorting downstream of the matrixby separating the flow onto a plurality of “lines,” such as by using aseries of parallel-running conveyors and a diverter (not shown) to routethe articles accordingly. The individual conveyors in these lines maythen form the infeed conveyors of a second matrix system (not shown),which can further sort the articles into even smaller sub-groups. Theprocess may repeat as necessary to create the desired degree or “level”of sortation for a particular operation.

Rather than using a matrix system 10 to deliver articles from a storagelocation, it may find utility in a converse arrangement. For example,upon receiving a delivery, the articles (boxes, packages, etc.)requiring sortation may transfer to an infeed conveyor at the warehousethat ultimately splits into a plurality of the infeed conveyors 12 ofthe matrix system 10. Sortation of the articles may follow as describedabove to place all those with a common parameter or characteristic on aparticular takeaway conveyor 14 for delivery to a particular storagelocation in the warehouse (e.g., one for books on a certain topicreside, books having a title beginning with a particular letter of thealphabet reside, etc.). The takeaway conveyors 14 can then be switchedto infeed conveyors 12 for delivering articles for delivery back to thematrix 10, which would then sort those articles having the commoncharacteristic that triggers transfer to the takeaway conveyors (whichformerly served as infeed conveyors).

In accordance with still another aspect of the invention, the matrixsystem 10 may also include three or more levels of conveyors. Forexample, the third conveyors of this level may receive selected articlesfrom the second takeaway conveyors for delivery to differentdestinations. Alternatively, these third conveyors may serve as secondinfeed conveyors for delivering articles to takeaway conveyors 14 alsocommon to the first infeed conveyors 12, or instead may also receivearticles from the infeed conveyors and thus function as a second set oftakeaway conveyors.

In the latter case, the third conveyors preferably extend parallel tothe second takeaway conveyors 14 and may lie either above or below theinfeed conveyors 12 (with corresponding means, such as chutes or poweredelevators, used to transfer the articles depending on the orientationused). However, the third conveyors preferably run in a directionopposite that of the takeaway conveyors 14 and are associated withdownstream sub-sortation stations (either individuals for placing theobjects in bins, automated sorters for doing so, etc.). This is shown inFIG. 7 by opposing arrows B and C along the takeaway conveyors 14 andthe third conveyors 34, respectively (with arrows A and D also showingthat the infeed conveyors 12 may also run in different directions). Themeans for transferring articles may include a transfer conveyor 16similar to the one described above, but capable of elevating thearticles in a reliable fashion (such as by using a high-frictionsurface, scoops, cleats, a “wedge” conveyor, or similar types ofarrangements that are well known in the art for reliably conveyingarticles against gravity). As perhaps best understood with reference toFIG. 8, it is also preferable for the transfer conveyor 16 to terminatein a plane above the corresponding third conveyor 34, such thattransferred articles simply drop onto the conveying surface.

As should be appreciated, a matrix system 10 with two or more sets oftakeaway conveyors may provide several advantages in use. For example,in the case of two levels of takeaway conveyors 14, 34, the ability totransfer articles from the infeed conveyor 12 to either a second orthird takeaway conveyor 14 or 34 during a single run can significantlyincrease the potential throughput of the system 10. This increaseresults without a corresponding increase in the conveying speed, whichhelps to make the overall operation more relaxed and effective than mostconventional approaches.

Another possibility involves alternating between the two levels oftakeaway conveyors 14, 34 in the matrix sorter system 10. For example,the lower takeaway conveyors 14 used in conjunction with the infeedconveyors 12 may sort a first batch or group of articles introduced tothe system 10. After the articles comprising the first batch move fromthe infeed conveyors 12, a second group of articles (of the same or adifferent type) may be introduced to the system 10 and transferred tothe upper takeaway conveyors 34 while the first group are simultaneouslybeing conveyed and sorted downstream on the lower takeaway conveyors 14.Using such an arrangement may allow for continuous operation of thesystem 10, despite the possible need for periodic downtime with onelevel of takeaway conveyors 14 or 34 after sorting a batch of articles(such as to address mis-sorted articles or situations where one or morearticles are incorrectly introduced into the system and need to bereplaced to fill a particular order).

Still another possible use of a matrix system involves operating only aportion of the infeed conveyors 12 at a given time. For example, in thearrangement shown in FIG. 4, only one of four groups G₁, G₂, G₃, G₄ offive infeed conveyors 12 may deliver articles to the takeaway conveyors14 (or deliver articles from only a certain storage location in awarehouse) during a first shift, with other groups used during differentshifts. This maintains constant wear on the conveyors of the variousgroups and also extends their service life. At times when an increasednumber of articles require sortation (i.e., at Christmas), then allcorresponding infeed conveyors 12 present may run simultaneously.

An alternative means for transferring articles between the conveyors 12,14 may comprise a separately actuatable drop-down portion 36 of theassociated infeed conveyor 12 (see FIGS. 9 and 10, as well as U.S. Pat.No. 4,426,074, the disclosure of which is incorporated herein byreference). Obviously, these drop down portions 36 would be placed at ornear the intersections with the takeaway conveyors 14, which as shouldbe appreciated represent possible or potential transfer points.

In the case of drop down portions 36, offsetting or “staggering” thetransfer points along the lateral extent of the takeaway conveyors 14a-14 d comprising the system 10 prevents collisions among articlestransferred from upstream infeed conveyors (such as infeed conveyors 12a-12 c in the case of four). FIG. 9 illustrates this approach by makingeach second or takeaway conveyor 14 wider than the associated first orinfeed conveyor 12 (note phantom portion), and/or by selectivelypositioning the end of the drop down portion 36. This allows for theeasy and efficient placement of articles at different locations alongthe width of the takeaway conveyor 14, while preventing collisions witharticles delivered from an upstream transfer point associated with adifferent infeed conveyor 12. In other words, the initial location ofeach article upon transfer may be staggered along the lateral dimensionof the associated takeaway conveyor 14. This is illustrated by showingpackages or parcels P₁ and P₂ in a side-by-side configuration in FIG. 10(which shows the actual transfer of the second package or parcel P₂ tothe takeaway conveyor 14 via the delivery end of a “staggered” drop downportion 36).

The foregoing descriptions of various embodiments of sorter systems andrelated methods provide illustration of the inventive concepts. Thedescriptions are not intended to be exhaustive or to limit the disclosedinvention to the precise form disclosed. Modifications or variations arealso possible in light of the above teachings. For example, theconveyors 12, 14, 16, 34 if comprised of modular links may be providedwith specialized links or rollers to facilitate article transfer (see,e.g., U.S. Pat. No. 6,874,617 to Layne, the disclosure of which isincorporated herein by reference). Also, it should be appreciated thatbooks are mentioned merely to illustrate one possible type of articlecapable of being conveyed or sorted using the disclosed inventions. Theembodiments described above were chosen to provide the best applicationto thereby enable one of ordinary skill in the art to utilize theinventions in various embodiments and with various modifications as aresuited to the particular use contemplated (such as, again, for conveyingor sorting articles other than books). All such modifications andvariations are within the scope of the invention.

The invention claimed is:
 1. A conveyor system for intended use inconjunction with the sorting of articles, comprising: a plurality offirst substantially continuous endless belt or chain conveyors extendingin a first direction, each providing a first continuous, uninterruptedconveying surface for the articles; and a plurality of secondsubstantially continuous endless belt or chain conveyors extending in asecond direction, each of said first conveyors overlapping the pluralityof second conveyors, each at least one of said second conveyorsproviding a second conveying surface below at least one of the firstconveyors, said second conveying surface arranged for conveying anyarticles transferred from one or more of the first conveyors, wherein anintersection is formed between each first conveyor and second conveyor,and wherein the first conveyors are positioned above the secondconveyors; and means adjacent each intersection for transferring one ormore articles from each first conveyor to the associated second conveyoradjacent the intersection, said means comprising a portion of each firstconveyor capable of assuming a drop down position for delivering one ormore of the articles to the second conveyor.
 2. The system according toclaim 1, wherein an end of the drop down portion of each first conveyoris staggered relative to a lateral dimension of the associated secondconveyor.
 3. The system according to claim 1, wherein the belts orchains of the first conveyors include conveying surfaces havinglongitudinal dimensions that are parallel to each other and generallyperpendicular to the longitudinal dimensions of the conveying surfacesof the belts or chains of the second conveyors.
 4. The system accordingto claim 1, wherein a longitudinal dimension of the first conveyingsurface of at least one first conveyor extends generally perpendicularto a longitudinal dimension of the second conveying surface of at leastone second conveyor.
 5. The system according to claim 1, wherein thefirst and second conveyors are chain conveyors including interconnectedmodular links.
 6. The system according to claim 1, further including aplurality of third conveyors for receiving articles from the first orsecond conveyors, wherein the third conveyors intersect the firstconveyors and extend generally parallel to the second conveyors.
 7. Thesystem according to claim 6, wherein the third conveyors move thearticles in a direction generally opposite that of the second conveyors.8. The conveyor system of claim 1, wherein each of the first and secondconveyors comprises a linear conveyor having a starting point at one endand an end point at a second end.
 9. The conveyor system of claim 1,wherein each first conveyor overlaps any one second conveyor only onetime.
 10. A conveyor system for intended use in conjunction with thesorting of articles, comprising: a plurality of first conveyorsextending in a first direction in a first horizontal plane; a secondconveyor extending in a second direction generally perpendicular to thefirst direction and in a second horizontal plane, the second conveyoroverlapping the plurality of first conveyors at each intersectionbetween the second conveyor and the plurality of first conveyors; andmeans adjacent each intersection for transferring at least one articlebetween the first and second conveyors.
 11. The system according toclaim 10, wherein the transferring means is a transfer conveyor.
 12. Thesystem according to claim 10, wherein the transfer conveyor is L-shapedand includes a first portion aligned with the first conveyor and asecond portion aligned with the second conveyor.
 13. The systemaccording to claim 12, wherein the second portion is tilted relative toa horizontal plane such that articles may slide onto the secondconveyor.
 14. The system according to claim 10, wherein the transferringmeans is selected from the group consisting of an active conveyor, apassive chute, and an elevator.
 15. The system according to claim 10,wherein the second conveyor is positioned below the plurality of firstconveyors.
 16. The system according to claim 10, wherein the secondconveyor is positioned above the plurality of first conveyors.
 17. Thesystem according to claim 10, further including means for moving the atleast one article from the first conveyor to the transferring means. 18.The system according to claim 17, wherein the moving means is a diverterassociated with the first conveyor.
 19. The system according to claim10, wherein the first conveyors comprise endless belt or chainconveyors.
 20. The conveyor system of claim 10, wherein each of thefirst and second conveyors comprises a linear conveyor having a startingpoint at one end and an end point at a second end.
 21. The conveyorsystem of claim 10, wherein each first conveyor overlaps the secondconveyor only one time.
 22. The system according to claim 10, whereinthe second conveyor includes a movable section that, in a homecondition, at least partially overlies at least one of the firstconveyors and spans between two adjacent sections of the secondconveyor.
 23. A conveyor system for intended use in conjunction with thesorting of articles, comprising: a plurality of first conveyorsextending in a first direction; a plurality of second conveyorsoverlapping the first conveyors; and a third conveyor for transferringarticles from a first conveyor to a second conveyor at eachintersection, wherein the third conveyor is L-shaped and includes afirst portion aligned with the first conveyor and a second portionaligned with the second conveyor.
 24. The system according to claim 23,wherein the second portion is tilted relative to a horizontal plane suchthat articles may slide onto the second conveyor.
 25. A conveyor systemfor intended use in conjunction with the sorting of articles,comprising: a plurality of first substantially continuous endless beltor chain conveyors extending in a first direction, each providing afirst conveying surface for the articles; a plurality of secondsubstantially continuous endless belt or chain conveyors extending in asecond direction and intersecting the first conveyors, each secondconveyor providing a second conveying surface for any articlestransferred from one or more of the intersecting first conveyors; andmeans for transferring at least one article from at least one of thefirst conveyors to an intersecting one of the second conveyors.
 26. Thesystem according to claim 25, wherein the belts or chains of the firstconveyors include conveying surfaces having longitudinal dimensions thatare parallel to each other and generally perpendicular to thelongitudinal dimensions of the conveying surfaces of the belts or chainsof the second conveyors.
 27. The system according to claim 25, wherein alongitudinal dimension of the first conveying surface of at least onefirst conveyor extends generally perpendicular to a longitudinaldimension of the second conveying surface of at least one secondconveyor.
 28. The system according to claim 25, wherein the first andsecond conveyors are chain conveyors including interconnected modularlinks.
 29. The system according to claim 25, further including aplurality of third conveyors for receiving articles from the first orsecond conveyors, wherein the third conveyors intersect the firstconveyors and extend generally parallel to the second conveyors.
 30. Thesystem according to claim 29, wherein the third conveyors move thearticles in a direction generally opposite that of the second conveyors.